Interlayer film for laminated glass and laminated glass

ABSTRACT

It is an object of the present invention to provide an interlayer film for a laminated glass excellent in a sound-insulating property, which is preferably usable for a head up display and the like wherein a driver can look at the front view and an instrument display simultaneously without requiring to look down, and to provide a laminated glass. 
     The present invention is directed to interlayer film for a laminated glass, which comprises at least a pair of protection layers and a sound-insulating layer sandwiched between the pair of the protection layers, and which has a wedge shape as a cross-sectional shape, a wedge angle θ of 0.1 to 0.7 mrad, the maximum thickness of 2000 μm or thinner, and the minimum thickness of 400 μm or thicker, the minimum thickness of the sound-insulating layer being 20 μm or thicker.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/193,458, filed Feb. 28, 2014, which is acontinuation application of U.S. patent application Ser. No. 13/230,400,filed Sep. 12, 2011, which is a continuation application of U.S. patentapplication Ser. No. 12/983,376, filed Jan. 3, 2011, now U.S. Pat. No.8,033,360, which application is a continuation of U.S. patentapplication Ser. No. 11/883,177, filed Aug. 31, 2007, now U.S. Pat. No.7,886,871, which application is a 35 U.S.C. 371 National StageApplication of International Application No. PCT/JP2007/059759, filedMay 11, 2007, which application claims priority to Japanese ApplicationNo. 2006-134200, filed May 12, 2006, the contents of each which areincorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to an interlayer film for a laminatedglass excellent in a sound-insulating property, which is preferablyusable for a head up display and the like wherein a driver can look atthe front view and an instrument display simultaneously withoutrequiring to look down, and relates to a laminated glass.

BACKGROUND ART

As so-called front glass, generally laminated glass composed of twoopposed plate-like glass sheets and an interlayer film for a laminatedglass sandwiched between the glass sheets has been used for the frontface of an automobile, an aircraft or the like.

In recent years, from a viewpoint of safety improvement, with respectto, for example, a front glass for an automobile, it has been highlyrequired to display an instrument display such as a speed information,which is automotive driving data, as a head up display (HUD) in the samevisible field as the front glass.

Various kinds of HUD mechanisms have been developed so far. For example,there is a HUD mechanism whose HUD display part is not in the frontglass surface and by which the speed information and the liketransmitted from a control unit is reflected to the front glass from adisplay unit on an instrumental panel to enable a driver to see theinformation at the same position as the front glass (that is, in thesame visible field). For such a mechanism, since the laminated glasscomposing the front glass comprises two parallel glass sheets, there isa defective point that the instrument display reflected in the visiblefield of the driver is seen double.

To deal with such a problem, Patent Document 1 discloses a laminatedglass using an interlayer film for a laminated glass with a wedge shapehaving a prescribed wedge angle.

Such a laminated glass enables a convergence of the instrument displayreflected by one glass sheet and the instrument display reflected by theother glass sheet upon one point in the visible field of the driver byadjusting the wedge angle, and the laminated glass can solve theconventional problem that the instrument display is seen double, and thedriver's visible field is never interfered.

However, such a laminated glass has a problem of inferiorsound-insulating property in particular.

-   Patent Document 1: Japanese Kokai Publication Hei-4-502525

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In view of the above-mentioned state of the art, the present inventionaims to provide an interlayer film for a laminated glass excellent in asound-insulating property, which is preferably usable for a head updisplay and the like wherein a driver can look at the front view and aninstrument display simultaneously without requiring to look down, andaims to provide a laminated glass.

Means for Solving the Problems

The present invention provides interlayer film for a laminated glass,which comprises at least a pair of protection layers and asound-insulating layer sandwiched between the pair of the protectionlayers, and which has a wedge shape as a cross-sectional shape, a wedgeangle θ of 0.1 to 0.7 mrad, the maximum thickness of 2000 μm or thinner,and the minimum thickness of 400 μm or thicker, the minimum thickness ofthe sound-insulating layer being 20 μm or thicker.

Hereinafter, the present invention will be described in detail.

The present inventors made various investigations concerning causes ofthe inferiority of the sound-insulating property of the laminated glassusing the interlayer film for a laminated glass with a wedge shape andaccordingly have found that since the interlayer film for a laminatedglass has a wedge angle, the thickness of the end forming the wedgeangle is extremely thin as compared with the other end and soundvibration is transmitted to the inside of a vehicle through the thinportion. Further, the inventors of the present invention have found thatthe problem that the instrument display reflected to the visible fieldof a driver is seen double cannot be solved only by making the thicknessof the end forming the edge angle in the interlayer film for a laminatedglass thick enough not to transmit the sound vibration. Therefore, theinventors of the present invention have made further investigations tofind that an interlayer film for a laminated glass having asound-insulating layer and a protection layer with prescribed thicknessand having a wedge angle in a prescribed range and a specified shapeovercomes the problems in terms of the lightweight, cost and the like,has sufficient sound-insulating property and penetration resistance,enables a driver to simultaneously see the front view, a speed displayand the like with no need for the driver to look down, and is preferablyusable for a head up display. These findings have now led to completionof the present invention.

An interlayer film for a laminated glass of the present inventioncomprises at least a pair of protection layers and a sound-insulatinglayer sandwiched between the pair of the protection layers.

The minimum thickness of the sound-insulating layer is 20 μm in thelower limit. If it is thinner than 20 μm, sufficient sound-insulatingproperty cannot be obtained. The lower limit is preferably 30 μm andmore preferably 40 μm. The upper limit is preferably 300 μm and morepreferably 200 μm.

As the thickness of the sound-insulating layer becomes thicker, a highersound-insulating property can be obtained. The cross-sectional shape ofthe sound-insulating layer may be a wedge shape in consideration of theeasiness in terms of formation and the like. In the case where thesound-insulating layer of the interlayer film for a laminated glass hatsa wedge shape, it has an excellent defoaming property of preventingfoaming in the laminated glass.

In this description, the wedge shape means a shape which is wide in oneend and becomes narrower toward the other end. Practical examples of theshape may be a trapezoidal shape and a triangular shape.

The sound-insulating layer may have partially a colored hand.

The colored band can be obtained, for example, by inserting a polyvinylacetal resin mixed with a coloring agent in a layer andextrusion-molding the resin at the time of extrusion-molding thesound-insulating layer.

The sound-insulating layer is not particularly limited, however it ispreferably to form the layer, for example, by using a plasticizer and apolyvinyl acetal resin.

The plasticizer is not particularly limited and may include, forexample, organic plasticizers such as monobasic organic acid esters andpolybasic organic acid esters; and organic phosphoric acid esterplasticizers such as organic phosphoric acid esters and organicphosphorous acid esters.

The monobasic organic acid ester plasticizers are not particularlylimited and may include, for example, glycol esters obtained by reactionwith glycols such as triethylene glycol, tetraethylene glycol, andtripropylene glycol and monobasic organic acids such as butyric acid,isobutyric acid, caproic acid, 2-ethylbutyric acid, heptylic acid,n-octylic acid, 2-ethylhexylic acid, pelargonic acid (n-nonylic acid),and decylic acid. Among them, triethylene glycol esters such astriethylene glycol dicaproate, triethylene glycol di-2-ethylbutanoate,triethylene glycol di-n-octanoate, triethylene glycoldi-2-ethylhexanoate (3GO) are preferable.

The polybasic organic acid ester plasticizers are not particularlylimited and may include, for example, esters obtained by reaction ofstraight chain or branched alcohols having 4 to 8 carbon atoms andpolybasic organic acids such as adipic acid, sebacic acid, and azelaicacid. Among them, dibutyl sebacate, dioctyl azelate, and dibutylcarbitoladipate are preferable.

The organic phosphoric acid ester plasticizers are not particularlylimited and may include, for example, tributoxyethyl phosphate,isodecylphenyl phosphate, and triisopropyl phosphate.

Among the plasticizers, triethylene glycol di-2-ethylbutanoate andtriethylene glycol di-2-ethylhexanoate (3GO) are preferably usable inparticular.

The content of the plasticizer in the sound-insulating layer is notparticularly limited, however since a higher sound-insulating propertycan be obtained by adding a large quantity of a plasticizer and therebysoftening the resin layer and absorbing the vibration of sound, it ispreferably 40 parts by weight in the lower limit and 80 parts by weightin the upper limit to 100 parts by weight of a polyvinyl acetal resin.If it is less than 40 parts by weight, the sound-insulating property forthe sound in a range about 5000 Hz may sometimes become insufficient andif it exceeds 80 parts by weight, bleeding out of the plasticizer occursto lower the transparency and the adhesive property of the interlayerfilm for a laminated glass and the optical distortion of the obtainedlaminated glass may become significant in some cases. It is morepreferably 50 parts by weight in the lower limit and 70 parts by weightin the upper limit.

The polyvinyl acetal resin is not particularly limited, however thesound-insulating layer contains a large quantity of the plasticizer asdescribed above, and therefore, the polyvinyl acetal resin is preferableto have high affinity even for a large quantity of the plasticizer.Particularly preferable examples to be used are a polyvinyl acetal resinhaving an acetal group having 4 to 5 carbon atoms and having anacetylation degree of 4 to 30% by mole, a polyvinyl acetal resin havingan acetal group having 6 to 10 carbon atoms, and a polyvinyl acetalresin having an acetalization degree of 70 to 85% by mole.

The polyvinyl acetal resin can be obtained by acetalization of polyvinylalcohol with aldehyde and generally includes an acetal group, an acetylgroup, and a hydroxy group as side chains in an ethylene chain, which isa main chain.

The average polymerization degree of the polyvinyl alcohol, which is araw material for producing the polyvinyl acetal resin, is preferably 200in the lower limit and 5000 in the upper limit. If it is lower than 200,the interlayer film for a laminated glass may sometimes be inferior inthe penetration resistance and if it exceeds 5000, the strength of thelaminated glass may sometimes become too high to use the glass for afront glass for a vehicle. It is more preferably 500 in the lower limitand 4000 in the upper limit and even more preferably 1000 in the lowerlimit and 3500 in the upper limit.

An aldehyde having 4 to 5 carbon atoms to be used for producing thepolyvinyl acetal resin having an acetal group having 4 to 5 carbon atomsis not particularly limited and may include, for example,n-butyraldehyde, isobutyraldehyde, and valeraldehyde. These aldehydesmay be used alone or two or more of them may be used in combination.Among them, n-butyraldehyde and isobutyraldehyde are preferable to beused and n-butyraldehyde is even more preferable to be used inparticular. Use of n-butyraldehyde strengthens the adhesive strengthbetween neighboring layers. Further, resins may foe synthesized in thesame methods as those for producing commonly used polyvinyl butyralresin.

With respect to the polyvinyl acetal resin having an acetal group having4 to 5 carbon atoms, the acetylation degree is preferably 4% by mole inthe lower limit and 30% by mole in the upper limit. If it is lower than4% by mole, the sound-insulating property is not exhibited sufficientlyin some cases and if it exceeds 30% by mole, the reaction ratio of thealdehyde is considerably lowered in some cases. It is more preferably 8%by mole in the lower limit and 24% by mole in the upper limit and evenmore preferably 10% by mole in the lower limit.

The acetylation degree is a mole fraction calculated by dividing theaverage value of the quantity of ethylene groups to which the acetylgroup is bonded by the total quantity of ethylene groups in the mainchain.

With respect to the polyvinyl acetal resin having an acetal group having4 to 5 carbon atoms, the acetalization degree is preferably 40% by molein the lower limit and 69% by mole in the upper limit. If it is lowerthan 40% by mole, the compatibility for the plasticizer is worsened tomake it impossible to add a necessary amount of the plasticizer toexhibit the sound-insulating property in some cases. On the other hand,a polyvinyl acetal resin having the acetalization degree exceeding 69%by mole is inferior in the production efficiency and becomes costly. Itis more preferably 50% by mole in the lower limit and 68% by mole in theupper limit.

With respect to the polyvinyl acetal resin having an acetal group having4 to 5 carbon atoms, a mixture of two or more kind polyvinyl acetalresins obtained by acetalization of polyvinyl alcohol with aldehydeshaving 4 carbon atoms or aldehydes having 5 carbon atoms. Alternatively,a polyvinyl acetal resin obtained by acetalization of an aldehydemixture containing an aldehyde other than the aldehyde having 4 to 5carbon atoms in a range of lower than 30% by weight may be used.

An aldehyde having 6 to 10 carbon atoms to be used for producing thepolyvinyl acetal resin containing an acetal group having 6 to 10 carbonatoms is not particularly and may include, for example, aliphatic,aromatic, or alicyclic aldehydes such as n-hexyl aldehyde,2-ethylbutyraldehyde, n-heptaldehyde, n-octyl aldehyde, n-nonylaldehyde, n-decyl aldehyde, benzaldehyde, and cinnamaldehyde. Thesealdehydes may be used alone or two or more of them may be used incombination. Among them, aldehydes having 5 to 8 carbon atoms arepreferably usable.

If the number of carbon atoms of the aldehyde exceeds 10, the rigidityof the polyvinyl acetal to be obtained becomes low and thesound-insulating property may be deteriorated in some cases.

With respect to the polyvinyl acetal resin having an acetalizationdegree of 70 to 85% by mole, the acetalization degree is preferably 70%by mole in the lower limit and 85% by mole in the upper limit. If it islower than 70% by mole, the sound-insulating property is not exhibitedsufficiently in some cases and if it exceeds 35% by mole, the reactionratio of the aldehyde to be used at the time of producing the polyvinylacetal resin may be considerably decreased in some cases. It is morepreferably 72% by mole in the lower limit and 82% by mole in the upperlimit.

The acetalization degree is a mole fraction calculated by dividing theaverage value of the quantity of ethylene groups to which the acetalgroup is bonded by the total quantity of ethylene groups in the mainchain.

A production method of the polyvinyl acetal resin is not particularlylimited and may be, for example, a method for obtaining a resin powderby dissolving polyvinyl alcohol in hot water, keeping the obtainedaqueous polyvinyl alcohol solution at a prescribed temperature, addingthe aldehyde and a catalyst to the solution, promoting acetalizationreaction, keeping the reaction solution at a prescribed hightemperature, and thereafter carrying out steps of neutralization,washing with water, and drying.

The sound-insulating layer is sandwiched between a pair of protectionlayers.

The protection layer prevents the adhesive property between theinterlayer film for a laminated glass and glass from lowering because ofbleeding out of a large quantity of the plasticizer contained in thesound-insulating layer. Further, the protection layer has a role toprovide the penetration resistance to the interlayer film for alaminated glass to be obtained. Further, the protection layer also has afunction of adjusting the shape of the entire interlayer film for alaminated glass to be a wedge shape.

The thickness of the protection layer may be adjusted in a manner thatthe film thickness of the entire interlayer film for a laminated glassis to be in a range as described below and is thus not particularlylimited.

The cross-sectional shape of the pair of the protection layers ispreferably the wedge shape or a combination of the wedge shape and arectangular shape.

The protection layer is not particularly limited, however it preferablycomprises a polyvinyl acetal resin containing a plasticizer.

The polyvinyl acetal resin to be used for the protection layer is notparticularly limited and may be, for example, a polyvinyl acetal resinhaving an acetylation degree of 3% by mole or lower, 3 to 4 carbon atomsof an acetal group, and an acetalization degree of 60 to 70% by mole.

The plasticizer to be used for the protection layer is not particularlylimited and the plasticizers same as those to be used for thesound-insulating layer may be used.

The content of the plasticizer in the protection layer is notparticularly limited, however it is preferably 25 parts by Weight in thelower limit and 55 parts by weight in the upper limit to 100 parts byweight of the polyvinyl acetal resin. If it is lower than 25 parts byweight, the adhesive property to the glass may become insufficient insome cases. Further, if it exceeds 55 parts by weight, bleeding outoccurs to lower the transparency and the adhesive property of theinterlayer film for a laminated glass and the optical distortion of theobtained laminated glass may become significant. It is more preferably30 parts by weight in the lower limit and 50 parts by weight in theupper limit.

Further, the protection layer may have partially a colored band.

The colored band can be obtained by inserting a polyvinyl acetal resinand the like mixed with a coloring agent in a layer andextrusion-molding the resin at the time of extrusion-molding theprotection layer.

In order to adjust the convenience and the shape in the productionmethod, a shape assisting layer may be layered on at least one layer ofthe pair of the protection layers.

The shape assisting layer is not particularly limited and the resin sameas that of the protection layer may foe used.

The thickness of the shape assisting layer may be adjusted in a mannerthat the film thickness, the wedge angle and the like of the interlayerfilm for a laminated glass to be obtained are to be in a range asdescribed below.

The sound-insulating layer, the protection layer, and/or the shapeassisting layer may contain, if necessary, conventionally knownadditives such as an ultraviolet ray absorbent, an adhesive strengthcontrol agent, a photostabilizer, a surfactant, a flame retardant, anantistatic agent, a moisture prevention agent, and a coloring agent.

The sound-insulating layer, the protection layer, and/or the shapeassisting layer are preferable to contain a heat insulating agent.

If the interlayer film for a laminated glass contains the heatinsulating agent in any one of the layers, the interlayer film for alaminated glass is provided with an excellent heat insulating property.

The heat insulating agent is not particularly limited and may include,for example, inorganic heat insulating agents such as tin-doped indiumoxide, antimony-doped tin oxide, and lanthanum hexaboride; and organicheat insulating agents such as copper complex compounds andphthalocyanine-metal complexes.

Practical Examples of cross-sectional drawings of the interlayer filmfor a laminated glass of the present invention comprising at least theprotection layers and the sound-insulating layer may be those shown inthe schematic drawings of FIGS. 1 to 4.

The interlayer film for a laminated glass shown in FIG. 1 comprises thesound-insulating layer 2 with a cross-sectional shape of the rectangularshape sandwiched between the protection layers 1 with a cross-sectionalshape of the wedge shape.

The interlayer film for a laminated glass shown in FIG. 2 comprises thesound-insulating layer 2 with a cross-sectional shape of the wedge shapesandwiched between the protection layers 1 with a cross-sectional shapeof the wedge shape.

The interlayer film for a laminated glass shown in FIG. 3 comprises thesound-insulating layer 2 with a cross-sectional shape of the rectangularshape sandwiched between the protection layer 1 with a cross-sectionalshape of the wedge shape and the protection layer 1 with across-sectional shape of the rectangular shape.

The interlayer film for a laminated glass shown in FIG. 4 comprises thesound-insulating layer 2 with a cross-sectional shape of the rectangularshape sandwiched between the protection layers 1 with a cross-sectionalshape of the rectangular shape and further a shape assisting layer 3with a cross-sectional shape of the wedge shape laminated on the surfaceof one of the protection layer.

Among them, the interlayer film for a laminated glass shown in FIG. 2 ispreferably since it has an excellent defoaming property of generating nofoam at the time of producing a laminated glass.

The interlayer film for a laminated glass of the present inventioncomprising at least the protection layers and sound-insulating layer hasa wedge angle θ of the cross-section of 0.1 mrad in the lower limit and0.7 mrad in the upper limit. The wedge angle θ of the cross-section ofthe interlayer film for a laminated glass means an acute angle formed atthe crossing point of extended two sides as shown as the wavy lines inthe cross-sectional drawings of FIGS. 1 to 4.

If the wedge angle θ is lower than 0.1 mrad, an instrument display forspeed information and the like transmitted from a control unit is seendouble and thus cannot display well and if it exceeds 0.7 mrad, theinstrument display is seen double in the visible field of a driver. Itis more preferably 0.2 mrad in the lower limit and 0.6 mrad in the upperlimit

The maximum thickness of the interlayer film for a laminated glass ofthe present invention is 2000 μm in the upper limit. The maximumthickness is the portion 4 as shown in FIG. 1.

If the maximum thickness exceeds 2000 μm, the thickness is too thick toinstall the laminated glass easily as the front glass in a vehicularbody in some cases. It is more preferably 1500 μm in the upper limit.

The minimum thickness of the interlayer film for a laminated glass ofthe present invention is 400 μm in the lower limit. The minimumthickness is the portion 5 as shown in FIG. 1.

If the minimum thickness is thinner than 400 μm, it becomes impossibleto obtain a sufficient sound-insulating property and the penetrationresistance to impact becomes weak. It is more preferably 500 μm in thelower limit.

A method for producing the sound-insulating layer, the protection layer,and the shape assisting layer is not particularly limited and may be,for example, methods involving adding a plasticizer and additives, addedbased on the necessity, to a polyvinyl acetal resin, kneading themixture, and molding the mixture. The kneading method is notparticularly limited and may be, for example, methods using an extruder,a Plastograph, a kneader, a Bumbury's mixer, a calender roll, or thelike. Among them, a method using an extruder is preferable since it issuitable for continuous production.

A method for producing the interlayer film for a laminated glass of thepresent invention comprising at least the sound-insulating layers andprotection layer is not particularly limited and may be methodsinvolving producing the protection layers and the sound-insulating layerand thermally laminating the layers; molding the protection layers andthe sound-insulating layer by co-extrusion; and molding the protectionlayers and the sound-insulating layer by co-extrusion, layering theshape assisting layer on the surface of at least one of the protectionlayers, and thermally laminating the layers.

Since the cross-sectional shape of the interlayer film for a laminatedglass is formed in a wedge shape by combining at least shapes of thesound-insulating layers and the protection layer, the sound-insulatingproperty is provided and the speed information and the like transmittedfrom the control unit can be reflected on the front glass from thedisplay unit of a instrumental panel and therefore, a driver cansimultaneously see the front view, speed display and the like withoutlooking down and the interlayer film for a laminated glass can be usedpreferably for a head up display.

A laminated glass obtained using the interlayer film for a laminatedglass of the present invention is also an aspect of the presentinvention.

The laminated glass of the present invention comprises at least theinterlayer film for a laminated glass of the present inventionsandwiched between a pair of glass sheets.

The glass sheets to be used are not particularly limited and may beconventionally known transparent plate glass. Further, organic glass ofpolycarbonate, polymethyl methacrylate or the like may be used in placeof inorganic glass.

A method for producing laminated glass of the present invention is notparticularly limited and conventionally known methods can be employed.

It is preferable to sandwich only one interlayer film for a laminatedglass between a pair of glass sheets since the laminated glassproduction is easy, however in terms of the properties and functionssuch as stability, a plurality of interlayer films for a laminated glassmay be sandwiched between a pair of glass sheets to produce a laminatedglass.

Effects of the Invention

According to the present invention, it is made possible to provide aninterlayer film for a laminated glass excellent in a sound-insulatingproperty, which is preferably usable for a head up display and the likewherein a driver can look at the front view and an instrument displaysimultaneously without requiring to look down, and to provide alaminated glass.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in details withreference to examples, however the present invention is not limited tothese examples.

Example 1 (1) Production of a Sound-Insulating Layer

A sound-insulating layer was produced by adding 65 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 12% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 65% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

(2) Production of a Protection Layer

A protection layer was produced by adding 38 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 1% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 68% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture.

(3) Production of an Interlayer Film for a Laminated Glass

The obtained sound-insulating layer was sandwiched between a pair ofprotection layers and thermally laminated to produce an interlayer filmfor a laminated glass with a cross-sectional shape of the wedge shape.The thickness of the interlayer film for a laminated glass and the wedgeangle of the cross-section were as shown in Table 1. The cross-sectionalshape was as shown in FIG. 2.

Example 2

A sound-insulating layer was produced by adding 65 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 1% by mole, 6 as the number of carbon atoms ox the acetal group, andan acetalization degree of 65% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

Thereafter, a protection layer was produced and successively aninterlayer film for a laminated glass was produced in the same manner asExample 1. The thickness of the interlayer film for a laminated glassand the wedge angle of the cross-section were as shown in Table 1. Thecross-sectional shape was as shown in FIG. 2.

Example 3

A sound-insulating layer was produced by adding 63 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 1% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 78% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

Thereafter, a protection layer was produced and successively aninterlayer film for a laminated glass was produced in the same manner asExample 1. The thickness of the interlayer film for a laminated glassand the wedge angle of the cross-section were as shown in Table 1. Thecross-sectional shape was as shown in FIG. 2.

Comparative Example 1

A sound-insulating layer was produced by adding 65 parts by weight oftriethylene glycol di-2-ethylhexanoate. (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 12% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 65% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

Thereafter, a protection layer was produced and successively aninterlayer film for a laminated glass was produced in the same manner asExample 1. The thickness of the interlayer film for a laminated glassand the wedge angle of the cross-section were as shown in Table 1. Thecross-sectional shape was as shown in FIG. 2.

Comparative Example 2

A sound-insulating layer was produced by adding 65 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 12% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 65% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

Thereafter, a protection layer was produced and successively aninterlayer film for a laminated glass was produced in the same manner asExample 1. The thickness of the interlayer film for a laminated glassand the wedge angle of the cross-section were as shown in Table 1. Thecross-sectional shape was as shown in FIG. 2.

Comparative Example 3

A sound-insulating layer was produced by adding 65 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 12% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 65% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

Thereafter, a protection layer was produced and successively aninterlayer film for a laminated glass was produced in the same manner asExample 1. The thickness of the interlayer film for a laminated glassand the wedge angle of the cross-section were as shown in Table 1. Thecross-sectional shape was as shown in FIG. 2.

Comparative Example 4

A sound-insulating layer was produced by adding 65 parts by weight oftriethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer to 100parts by weight of a polyvinyl acetal resin having an acetylation degreeof 12% by mole, 4 as the number of carbon atoms of the acetal group, andan acetalization degree of 65% by mole, sufficiently kneading themixture by a mixing roll, and extrusion-molding the mixture. Thethickness of the sound-insulating layer was as shown in Table 1.

Thereafter, a protection layer was produced and successively aninterlayer film for a laminated glass was produced in the same manner asExample 1. The thickness of the interlayer film for a laminated glassand the wedge angle of the cross-section were as shown in Table 1. Thecross-sectional shape was as shown in FIG. 2.

<Evaluation>

The following evaluations were carried out for the interlayer films fora laminated glass obtained in Examples 1 to 3 and Comparative Examples 1to 4. The results are shown in Table 1.

(1) Sound-Insulating Property

Each sample obtained by cutting obtained laminated glass into a size of300 mm×25 mm was vibrated by a vibration generating apparatus for adamping test (a vibrator G21-005D, manufactured by Shinken Co., Ltd.)and the vibration property obtained at that time was amplified by amechanical impedance amplifier (XG-81, manufactured by RION Co., Ltd.)and the vibration spectrum was analyzed by an FFT spectrum analyzer (FFTanalyzer HP3582A, manufactured by Yokogawa Hewlett Packard).

A graph showing the relation between sound frequency (Hz) and soundtransmission loss (dB) at 20° C. was produced from the ratio of lossfactor and the resonance frequency of the glass measured in the mannerto measure the minimum sound transmission loss (TL value) around a soundfrequency of 2000 Hz and the evaluation was carried out based on thefollowing standard. As the TL value is higher, the sound-insulatingproperty is higher.

◯: 35 dB or higher

X: lower than 35 dB.

(2) Occurrence of Double Image

Each obtained laminated glass was disposed at a position of a frontglass and display information was reflected upon the laminated glassfrom a display unit installed in a lower part and occurrence of a doubleimage at a prescribed position was confirmed by eye observation and theevaluation was carried out based on the following standard.

◯: No double image was confirmed.

X: A double image was confirmed.

(3) Defoaming Property Evaluation

A laminate body was produced by sandwiching each interlayer film for alaminated glass between two transparent float glass plates (length 30cm, width 30 cm, thickness 3 mm).

The obtained laminate body was put in a rubber bag and held at a reducedpressure of −60 kPa (absolute pressure 16 kPa) for 10 minutes and heatedin order that the temperature of the laminate body reach 100° C. andthen taken out of the rubber bag. Next, it was put in an autoclave andheld at a temperature of 140° C. and a pressure of 1.3 MPa for 10minutes and then taken out of the autoclave after the temperature of theinside of the autoclave was decreased to 50° C. In such a manner, alaminated glass was produced.

The obtained laminated glass was heated in an oven at 200° C. for 2hours. Next, the laminated glass was taken out of the oven and after 3hours, the appearance of the laminated glass was observed with eyes. Thenumber of sheets of the laminated glass in which foams with an outerdiameter of 1 mm or larger were formed was investigated. The number ofthe sheets of the laminated glass to be used in the test was 20. As thenumber of the sheets in which foams were formed was lower, theinterlayer film for a laminated glass was found having a more excellentdefoaming property. The results of the test were evaluated based on thefollowing standard.

⊚: One sheet of laminated glass was found foaming.

◯: Four sheets of laminated glass were found foaming.

TABLE 1 Sound-insulating layer Interlayer film for a laminated glassEvaluation Minimum Maximum Minimum Maximum Wedge Cross- TL Occurrencethickness thickness thickness thickness angle sectional value of doubleDefoaming (μm) (μm) (μm) (μm) (mrad) shape (dB) image property Example 1100 150 800 1200 0.40 FIG. 2 37 ○ ○ ⊚ Example 2 100 150 700 1100 0.30FIG. 2 36 ○ ○ ⊚ Example 3 80 200 600 1200 0.58 FIG. 2 35 ○ ○ ⊚Comparative 100 120 700 800 0.08 FIG. 2 37 ○ × ⊚ Example 1 Comparative15 30 800 1200 0.40 FIG. 2 31 × ○ ⊚ Example 2 Comparative 20 30 300 4500.30 FIG. 2 31 × ○ ⊚ Example 3 Comparative 100 150 800 1600 0.80 FIG. 237 ○ × ⊚ Example 4

Examples 4 and 5

Each interlayer film for a laminated glass was produced in the samemanner as Example 1, except that the cross-sectional shape was adjustedto be the wedge shape as shown in FIG. 1 and the thickness of thesound-insulating layer, the thickness of the interlayer film for alaminated glass, and the wedge angle were changed as shown in Table 2.

Comparative Examples 5 and 6

Each interlayer film for a laminated glass was produced in the samemanner as Example 1, except that the cross-sectional shape was adjustedto be the wedge shape as shown in FIG. 1 and the thickness of thesound-insulating layer, the thickness of the interlayer film for alaminated glass, and the wedge angle were changed as shown in Table 2.

<Evaluation>

With respect to each interlayer film for a laminated glass obtained inExamples 4 and 5 and Comparative Examples 5 and 6, same evaluationscarried out for Examples 1 to 3 and Comparative Examples 1 to 4 werecarried out. The results are shown in Table 2.

TABLE 2 Sound-insulating layer Interlayer film for a laminated glassEvaluation Minimum Maximum Minimum Maximum Wedge Cross- TL Occurrencethickness thickness thickness thickness angle sectional value of doubleDefoaming (μm) (μm) (μm) (μm) (mrad) shape (dB) image property Example 4100 100 800 1200 0.40 FIG. 1 36 ○ ○ ○ Example 5 110 110 600 1200 0.58FIG. 1 35 ○ ○ ○ Comparative 100 100 800 890 0.08 FIG. 1 36 ○ × ○ Example5 Comparative 15 15 800 1200 0.40 FIG. 1 30 × ○ ○ Example 6

Example 6

An interlayer film for a laminated glass was produced in the same manneras Example 1, except that the cross-sectional shape was adjusted to bethe wedge shape as shown in FIG. 3 and the thickness of thesound-insulating layer, the thickness of the interlayer film for alaminated glass, and the wedge angle were changed as shown in Table 3.

Comparative Example 7

An interlayer film for a laminated glass was produced in the same manneras Example 1, except that the cross-sectional shape was adjusted to bethe wedge shape as shown in FIG. 3 and the thickness of thesound-insulating layer, the thickness of the interlayer film for alaminated glass, and the wedge angle were changed as shown in Table 3.

<Evaluation>

With respect to each interlayer film for a laminated glass obtained inExample 6 and Comparative Example 7, same evaluations carried out forExamples 1 to 3 and Comparative Examples 1 to 4 were carried out. Theresults are shown in Table 3.

TABLE 3 Sound-insulating layer Interlayer film for a laminated glassEvaluation Minimum Maximum Minimum Maximum Wedge Cross- TL Occurrencethickness thickness thickness thickness angle sectional value of doubleDefoaming (μm) (μm) (μm) (μm) (mrad) shape (dB) image property Example 6100 100 800 1200 0.40 FIG. 3 36 ○ ○ ○ wedge shape protection wedge shapeprotection layer: 350 layer: 750 rectangular shape rectangular shapeprotection layer: 350 protection layer: 350 Comparative 100 100 800 9000.08 FIG. 3 36 ○ × ○ Example 7 wedge shape protection wedge shapeprotection layer: 350 layer: 450 rectangular shape rectangular shapeprotection layer: 350 protection layer: 350

Examples 7 and 8

An interlayer film for a laminated glass was produced in the same manneras Example 1, except that the cross-sectional shape was adjusted to bethe wedge shape as shown in FIG. 4 and the thickness of thesound-insulating layer, the thickness of the interlayer film for alaminated glass, and the wedge angle were changed as shown in Table 4.The shape assisting layer was produced by using the resin with the samecomposition as that of the resin used for producing the protection layerin Example 1.

Comparative Examples 8 and 9

An interlayer film for a laminated glass was produced in the same manneras Example 1, except that the cross-sectional shape was adjusted to bethe wedge shape as shown in FIG. 4 and the thickness of thesound-insulating layer, the thickness of the interlayer film for alaminated glass, and the wedge angle were changed as shown in Table 4.The shape assisting layer was produced by using the resin with the samecomposition as that of the resin used for producing the protection layerin Example 1.

<Evaluation>

With respect to each interlayer film for a laminated glass obtained inExamples 7 and 8 and Comparative Examples 8 and 9, same evaluationscarried out for Examples 1 to 3 and Comparative Examples 1 to 4 werecarried out. The results are shown in Table 4.

TABLE 4 Sound-insulating layer Interlayer film for a laminated glassEvaluation Minimum Maximum Minimum Maximum Wedge Cross- TL Occurrencethickness thickness thickness thickness angle sectional value of doubleDefoaming (μm) (μm) (μm) (μm) (mrad) shape (dB) image property Example 7100 100 900 1300 0.40 FIG. 4 36 ○ ○ ○ wedge shape protection wedge shapeprotection layer: 200 layer: 200 rectangular shape rectangular shapeprotection layer: 200 protection layer: 200 shape assisting layer: 400shape assisting layer: 800 Example 8 100 100 900 1550 0.58 FIG. 4 36 ○ ○○ wedge shape protection wedge shape protection layer: 200 layer: 200rectangular shape rectangular shape protection layer: 200 protectionlayer: 200 shape assisting layer: 400 shape assisting layer: 1050Comparative 100 100 900 1100 0.08 FIG. 4 36 ○ × ○ Example 8 wedge shapeprotection wedge shape protection layer: 200 layer: 200 rectangularshape rectangular shape protection layer: 200 protection layer: 200shape assisting layer: 400 shape assisting layer: 600 Comparative 15 15900 1300 0.40 FIG. 4 30 × ○ ○ Example 9 wedge shape protection wedgeshape protection layer: 200 layer: 200 rectangular shape rectangularshape protection layer: 285 protection layer: 285 shape assisting layer:400 shape assisting layer: 800

INDUSTRIAL APPLICABILITY

According to the present invention, it is made possible to provide aninterlayer film for a laminated glass excellent in a sound-insulatingproperty, which is preferably usable for a head up display and the likewherein a driver can look at the front view and an instrument displaysimultaneously without requiring to look down, and to provide alaminated glass.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing schematically showing a cross-sectional drawing ofan interlayer film for a laminated glass of the present invention.

FIG. 2 is a drawing schematically showing a cross-sectional drawing ofan interlayer film for a laminated glass of another embodiment of thepresent invention.

FIG. 3 is a drawing schematically showing a cross-sectional drawing ofan interlayer film for a laminated glass of another embodiment of thepresent invent ion.

FIG. 4 is a drawing schematically showing a cross-sectional drawing ofan interlayer film for a laminated glass of another embodiment of thepresent invention.

EXPLANATION OF SYMBOLS

-   1 a protection layer-   2 a soured-insulating layer-   3 a shape assisting layer-   4 the maximum thickness-   5 the minimum thickness

What is claimed is:
 1. An interlayer film for a laminated glass, whichcomprises at least a pair of protection layers and a sound-insulatinglayer sandwiched between the pair of the protection layers, and whichhas a wedge shape as a cross-sectional shape, a wedge angle θ of 0.1 to0.7 mrad, the maximum thickness of 2000 μm or thinner, and the minimumthickness of 400 μm or thicker, the minimum thickness of thesound-insulating layer being 20 μm or thicker wherein thesound-insulating layer comprises a polyvinyl acetal resin and aplasticizer, and the content of the plasticizer in the sound-insulatinglayer is 50 parts by weight or more to 100 parts by weight of thepolyvinyl acetal resin, wherein the sound-insulating layer has a wedgeshape as its cross-sectional shape, and wherein the protection layershas a wedge shape as its cross-sectional shape.
 2. A laminated glass,which is obtained by using the interlayer film for a laminated glassaccording to claim
 1. 3. The interlayer film for a laminated glassaccording to claim 1, wherein the protection layer and/or thesound-insulating layer contain a heat-insulating agent.
 4. Theinterlayer film for a laminated glass according to claim 1, whichfurther comprises a shape assisting layer laminated on at least onelayer of the pair of the protection layers.
 5. The interlayer film for alaminated glass according to claim 4, wherein the protection layer, thesound-insulating layer, and/or the shape assisting layer contain aheat-insulating agent.
 6. A laminated glass, which is obtained by usingthe interlayer film for a laminated glass according to claim
 5. 7. Theinterlayer film for a laminated glass according to claim 4, wherein theprotection layer and/or the sound-insulating layer contain aheat-insulating agent.
 8. A laminated glass, which is obtained by usingthe interlayer film for a laminated glass according to claim
 7. 9. Alaminated glass, which is obtained by using the interlayer film for alaminated glass according to claim 4.